Optical Tweezers in Emulsion Research: Principles, Advances, and Prospects

Optical tweezers (OTs) have emerged as a powerful tool for probing emulsion dynamics with single-droplet precision, enabling quantitative analysis of interfacial interactions. Recent OT studies have systematically elucidated the critical factors governing emulsion stability, including ionic strength, pH, surfactant architecture, temperature, and photo/gas stimuli. Parallel advances in optofluidic control demonstrate that light-driven droplet rotation-achieved through angular momentum transfer and liquid crystal molecular reorientation represents a transformative approach for active soft matter manipulation. In this review, we conduct a systematic evaluation of OT systems, encompassing both instrumental configurations and cost-benefit analyses to assess their practical feasibility. The review critically examines the unique capabilities of OTs in emulsion research-including unprecedented spatial resolution and quantitative force measurement at the single-droplet level while addressing current limitations in throughput and operational complexity. Looking forward, the synergistic integration of OT technology with microfluidic platforms and machine learning algorithms is also presented.